1. Field of the Invention
The invention relates to a disk system that can easily recover from a failure, and to a factory automation (FA) controller using such disk system.
2. Description of the Background Art
FIG. 10 is a block diagram showing a configuration of a conventional FA controller. In FIG. 10, a disk system 101 comprises a CPU 2, a bus 2a connected between CPU 2 and disk interfaces 3a, 3b that are connected respectively to disk units 4a and 4b and serve to match signals between bus 2a and disk units 4a and 4b. A memory 107 is connected to bus 2a and has an area in memory 107a that stores a disk mirroring program. The disk mirroring program is designed to execute a duplicating operation for writing the same content to the two disk units, disk unit 4a and disk unit 4b, in the event of a failure.
Reference numeral 21 designates a main CPU of the FA controller that executes the applications program and has connected thereto a bus 21a. Reference numeral 122 designates a memory connected to bus 21a; and 122a is an area in memory 122 at which an application program is stored. Reference numeral 150 designates a console that can receive data through keys and that can display data; and 3 is a disk interface for matching a signal between bus 21a and bus 2a.
The disk mirroring program stored in area 107a is designed to not only write data that is transferred from main CPU 21 based on a disk writing instruction outputted from main CPU 21 during the normal operation to disk units 4a, 4b through disk interfaces 3a, 3b under the control of CPU 2, but also allow the operation of the FA controller to be continued by one of disk units 4a, 4b when the other one has failed. Main CPU 21 operates based on the above-mentioned application program.
FIG. 11 is a diagram illustrative of an exemplary location of console 150 and exemplary locations of the FA controller body and a programmable controller. FIG. 12 is an enlarged perspective view showing appearances of the FA controller body and the programmable controller installed in a factory in FIG. 11.
In FIG. 12, reference numeral 1202 designates the FA controller body which includes a main CPU 1201, comprising main CPU 21 and memory 122; and an interface 1204 dedicated to the FA controller shown in FIG. 10. The FA controller body 1202, as illustrated, shows portions of FA controller shown in FIG. 10 excluding console 150. Reference numeral 1203 designates the programmable controller connected to the FA controller.
In FIG. 11, reference numeral 1101 designates a case where console 150 is installed in an office of a factory; 1102, a case where console 150 is installed in a monitor room of the factory; 1103, the installation of FA controller body 1202 and programmable controller 1203 assembled into a machine; and 1104, the installation of FA controller 1202 and programmable controller 1203 assembled in a control panel.
Generally, as shown in FIG. 11, FA controller body 1202 and programmable controller 1203 are installed in the field of a factory, whereas console 150 is installed in an office or a monitor room remote from the field.
FIG. 13 shows an exemplary content to be displayed on console 150 while disk unit 4a that has failed during the operation of the disk mirroring program is being replaced with a good one. In console 150, disk unit 4a is indicated as disk unit A, and disk unit 4b is indicated by disk unit B.
In FIG. 13, reference numeral 601 designates a display message when disk unit 4a is in failure. When such display message is found on the screen, an operator switches disk unit 4a offline by inputting an instruction designated by 602 through the keys of console 150.
When disk unit 4a has been placed offline, such display messages as reference numeral 603 appear. The operator, after confirming these display messages, replaces disk unit 4a with a good one.
When the replacement of disk unit 4a has been completed, the operator puts disk unit 4a in an "online" state by operating the keys of console 150.
As disk unit 4a is online, such display messages as designated by 605 appear. The operator, after confirming these display messages, inputs such instructions as designated by 606 by operating the keys of console 150 to copy the content of disk unit 4b having the correct data to disk unit 4a.
Such a display message as designated by 607 appears during the copy operation; and upon end of the copy operation, such a display message as designated by 608 appears.
Since the conventional disk system and the conventional FA controller using such disk system are constructed as described above, when one of disk units 4a, 4b within disk system 101 has failed, the operation of confirming the failure, the replacement of the disk unit, and the copy operation of the disk unit must be instructed from console 150 connected to the main CPU. However, where such disk system or FA controller is installed in a field of a factory as shown in FIG. 12, i.e., a location remote from the disk unit that has failed in many cases. Since the console 150 operation alternates with the removal and installation of the disk in the replacement, the replacement is time-consuming. In addition, there is a case in which console 150 is not installed at all, and in such case console 150 must be connected expediently.